Delivery of drug to a specific treatment site represents a substantial challenge in the design of drug delivery systems. While drugs designed for action at or within a specific tissue or organ, e.g., the kidney, may be suitable for systemic delivery, the amount of drug delivered by this route often must be quite high if a therapeutically effective amount is to be delivered to the desired site. Delivery of large amounts of drug, however, can increase the likelihood and severity of side effects and can be otherwise disadvantageous, e.g., increased costs of therapy. One approach to addressing this issue is to use site-specific drug delivery, which can involve the use of a catheter positioned at a treatment site. Delivery of drug to a site within a tissue/organ, however, generally requires breaking the surface of the organ to implant the catheter tip within the tissue/organ. This may be undesirable where the tissue/organ is sensitive or already damaged and may compromise the integrity of structures surrounding the tissue/organ. Thus, other methods for tissue- or organ-specific drug delivery would be desirable.
The kidney is an organ of particular interest for organ-specific therapy. Diabetic nephropathy, for example, is a disease that develops over a prolonged period, 10-15 years, during which the ability of the kidneys to properly function diminishes. Diabetic nephropathy eventually leads to end-stage renal disease (ESRD), a condition that requires the individual to undergo dialysis or a kidney transplant to stay alive. A therapy that can slow or prevent patients from developing ESRD, or any other tissue or organ specific disease or disorder, without delivering high amounts of drug systemically would be extremely useful. The present invention provides such a therapy.